In a typical wireless network such as long-term evolution (LTE) network, the selection of shared data channels for uplink (UL) is scheduling/grant based, and the scheduling and grant mechanisms are controlled by a base station (BS) in a network. A user equipment (UE) sends an UL scheduling request to the base station. When the BS receives the scheduling request, the BS sends an UL grant to the UE indicating its UL resource allocation. The UE then transmits data on the granted resource.
An issue with this approach is that the signaling resource overhead for the scheduling/grant mechanism can be quite large, especially in cases where the data transmitted is small. For example, for small packet transmissions of around 20 bytes each, the resources used by the scheduling/grant mechanism could be around 30%, or even 50%, of the packet's size. Another issue with this approach is the scheduling/grant procedure causes an initial delay in data transmission. Even when the resources are available, there is a minimum 7-8 ms delay in a typical wireless network between a scheduling request being sent and the first uplink data transmission.